This app was mentioned in 3 comments, with an average of 3.00 upvotes
When did AndroidCentral start running Sponsored Content?
We have a [compatibility checker app.](https://play.google.com/store/apps/details?id=com.ting.compatibilitycheck\) It doesn't come with a fancy trial plan, but 100/100/100 is $15 on Ting, and any referral credit covers more than that!
In general, an S5 compares favorably with ~200 USD phones today. The CPU, for instance, is a Snapdragon 801 in the S5, and usually a 400 or 600 range Snapdragon in current 200 dollar phones; regardless of specific model, the 801 is better.
As for whether you can use an old pre-paid S5, the answer is that it depends. Some carriers sell modified phones for their pre-paid plans; these phones permanently have that carrier's SIM card, and can't be swapped out for another SIM card. In such a case, you could only use the phone through buying service through that carrier's pre-paid plans.
Here's what I would do: take that phone to an area with wifi, and from the Google Play store install the Ting Compatibility Checker app. Ting is an MVNO that requires a different SIM card; if the app says the phone is compatible with Ting, then you can likely use it with a wide variety of carriers.
There is a Ting Compatibility App you can download: https://play.google.com/store/apps/details?id=com.ting.compatibilitycheck